Are You Eating Too Much Protein?

Beloved protein has a dark side. In a recent study at UCLA, people 65 and under who ate a high-protein diet had four times the risk of death from cancer and diabetes and double the risk of death from any other cause. Protein activates IGF-1, a growth factor that pushes cells to age more quickly—which can cause DNA damage. Interestingly, moderate or high amounts of protein led to lower cancer and death rates for those over age 65. "Older adults tend to lose weight and be more frail, so for them, a boost in protein can benefit immunity," says study author Valter Longo.